# OS_ReferentSize

## C Specification

      #include <nitro/os.h>

      void OS_ReferentSize(
                  OSArenaId   id ,
                  void*       ptr );

## Description

Acquires the size that the specified main block occupies in memory, excluding the header region for managing the memory block

For information about this value see `OS_InitArena()`.

`ptr` is the address to the memory block that is previously acquired with `OS_AllocFixed()`, `OS_AllocFromHeap()`, etc.

## Arguments

`id` | ID of the arena associated with the memory block
`ptr` | Pointer to the memory block

## Return Values

Returns the size of the specified main block in memory, excluding the header region for managing the memory block.

## See Also

`OS_InitArena`, `OS_InitAlloc`, `OS_AllocFromHeap`, `OS_AllocFixed`

## Revision History

01/07/2004 Initial version